Had a few more practice attempts at these and then remade the Elm bark sheath, and the birch bark one I made for the Fast knife. Think I have it sorted now as I wasn't happy just winding the bark around spiral fashion so after a bit of research I managed to figure out the weaving method.
One turn round the outside, one turn between the front loop and rear loop. The side view should explain.
The whipping knots are there just to help secure the last few turns from coming loose over time.